The symptoms of narcosis may be caused by other factors during a dive: ear problems causing disorientation or nausea; early signs of oxygen toxicity causing visual disturbances; or hypothermia causing rapid breathing and shivering. Nevertheless, the presence of any of these symptoms should imply narcosis.
What's a Coronarita? It's a margarita with an upside-down Corona sticking out of it. Does it taste any good? You be the judge!
The cause is an irritated diaphragm when the stomach is distended by food, alcohol, air or stress. One case of chronic singultus (the medical term) lasted for sixty years. That's a long time to drink water upside down.